Pfizer-BioNTech and Moderna's Covid-19 vaccines are highly effective in preventing infections in real world conditions, says a new study by the US Centers for Disease Control and Prevention. Results showed that following the second dose of vaccine, risk of infection was reduced by 90 per cent two or more weeks after vaccination, the CDC said on Monday. Following a single dose of either vaccine, the participants' risk of infection with SARS-CoV-2 was reduced by 80 per cent two or more weeks after vaccination.
